Replace isnan() with better comparisons (isgreater(), etc.)

The standard isnan() function is defined to never throw FP exceptions
even when the argument is a "signaling" NaN. This makes isnan() more
expensive than (x != x) expression unless the compiler flag
'-fno-signaling-nans' is given.

Introduce functions isNaN(), isNonnegative(), isPositive(),
sumPositiveValues() and compareRealNumbers(), and replace isnan() in
htop's codebase with the new functions. These functions utilize
isgreater() and isgreaterequal() comparisons, which do not throw FP
exceptions on "quiet" NaNs, which htop uses extensively.

With isnan() removed, there is no need to suppress the warning
'-Wno-c11-extensions' in FreeBSD. Remove the code from 'configure.ac'.

Signed-off-by: Kang-Che Sung <explorer09@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/Process.c b/Process.c
index 57763b86..7e2d11af 100644
--- a/Process.c
+++ b/Process.c
@@ -757,7 +757,7 @@ void Process_printRate(RichString* str, double rate, bool coloring) {
       processMegabytesColor = CRT_colors[PROCESS];
    }
 
-   if (isnan(rate)) {
+   if (!isNonnegative(rate)) {
       RichString_appendAscii(str, shadowColor, "        N/A ");
    } else if (rate < 0.005) {
       int len = snprintf(buffer, sizeof(buffer), "%7.2f B/s ", rate);
@@ -790,7 +790,7 @@ void Process_printLeftAlignedField(RichString* str, int attr, const char* conten
 }
 
 void Process_printPercentage(float val, char* buffer, size_t n, uint8_t width, int* attr) {
-   if (val >= 0) {
+   if (isNonnegative(val)) {
       if (val < 0.05F)
          *attr = CRT_colors[PROCESS_SHADOW];
       else if (val >= 99.9F)